Media release 01.07.2005
Postponing first commercial thinnings by approximately ten years from the currently recommended time would improve the profitability of the first commercial thinnings without reducing the stand’s wood yield or economic outcome from the entire rotation period. This presupposes that the seedling stand management had been taken care at the right time. The above information was reported in a study made at the Finnish Forest Research Institute.
The research goal was to compare the effects of five alternative methods of first commercial thinning on the wood yield and economic profitability of a pine stand of dryish forest site type on mineral soil. The research material consisted of the machine-cut first thinning stands by Metsähallitus during 1999 and 2000, a total of 27 stands in the areas of central Finland, northern Ostrobothnia and southern Lapland.
When the recommended time of first commercial thinning was delayed by ten years, the yield of pulpwood was approximately doubled, from 30 to 60 cubic metres per hectare. Simultaneously, the current value of the stumpage earnings (with 4% interest rate) was increased on average by 330 € per hectare. Variation of stumpage prices or changes of interest rate did not have a crucial effect on the final results. Without exception, performing the first commercial thinning after a ten year delay resulted to be the most profitable method. Furthermore, the wood yield and economic outcome from the entire rotation period were approximately the same regardless of whether the first thinning was done at the time point currently recommended or ten years later.
According to the silvicultural guidelines of Metsähallitus the first commercial thinning should normally be performed when the typical dominant height of the pine stand reaches 12-14 metres. At this point a stand in central Finland would be 30-40 years old and in southern Lapland approximately 60 years old. In first commercial thinnings the amount of the remaining stand is defined primarily on the basis of the number of stems whereas in the subsequent silvicultural thinnings it is based on the stand’s basal area.
During 2003 first commercial thinnings were performed on a total of 170,000 hectares, which corresponds to less than one third of the total area of cuttings. In the future the proportion of forests of first-thinning age will increase.